The Brown administration, laboring to start building California's high-speed rail project by early next year, is preparing a proposal to insulate the project from environmental lawsuits, limiting circumstances in which a court may block construction of the line.

The proposal, criticized by environmentalists as it emerged on Friday, would protect the $68 billion project from court-ordered injunctions that might otherwise be issued under the California Environmental Quality Act.

Except in the most serious cases of potential environmental harm, the proposed legislation would allow construction to proceed while the California High-Speed Rail Authority fixes any environmental flaws identified by a judge.

The proposal is likely to be considered by the Legislature this month or next. Environmentalists expected to be briefed by administration officials on the plan next week.

Dan Richard, chairman of the rail authority board, said Friday that the proposal consists of "pretty small, pretty technical" changes. It would allow a judge to block construction in major cases – if opponents showed, for example, that an endangered species was threatened with extinction, he said.

Environmentalists are generally supportive of high-speed rail for the promise of mass transit. But the state's environmental quality act is its signature environmental protection, and environmentalists are almost certain to oppose the administration's proposal.

"I don't imagine that we're going to see something next week that will make us want to embrace these exemptions that they're going to be proposing," said Kathryn Phillips, director of Sierra Club California.

Among other things, environmentalists have objected to the administration's plan to run high-speed rail over Pacheco Pass west of Los Banos, where they fear its effect on wetlands.

Phillips said the rail authority's concern about environmental challenges slowing the project is misplaced.

"Environmental review is not going to slow this project," she said. "What's going to slow this project is ineptitude by the high-speed rail authority, and that's what we have seen, at least in the last four years."

In addition to raising standards for blocking construction, the proposal would make it easier for the administration to modify parts of the project without redoing its overall environmental review. For example, the rail authority could move forward with its recently adopted and widely praised plan to use existing infrastructure in urban areas without exposing itself to new litigation.

Stuart Flashman, an Oakland lawyer who has sued the California High-Speed Rail Authority on behalf of cities in the Bay Area, said it "makes it a real long-shot" for an opponent to block potentially damaging construction in court.

"If the Legislature passes this," he said, "both the Legislature and the governor ought to be ashamed of themselves."

The state has previously protected major projects from environmental challenges. Brown, a Democrat, signed legislation last year accelerating judicial review of environmental challenges to a proposed football stadium in Los Angeles.

At the time, he said the project was necessary to "get people working" in California.

Proponents of the high-speed rail project have made the same argument about high-speed rail.

The project is a major part of Brown's agenda, and the proposal to protect it from litigation could be significant to his ability to start construction in the Central Valley by next year.

On Friday, the city of Chowchilla became the latest litigant to file an environmental lawsuit against the project.

Brown is seeking legislative approval this summer to use $2.6 billion in state rail bond funds and $3.3 billion in federal funds to start construction of the rail line.

Senate President Pro Tem Darrell Steinberg, D-Sacramento, said Friday that he expects a vote on that appropriation to come after the state budget is considered this month but before the Legislature recesses for summer.

Steinberg said he doesn't anticipate a major floor debate about the California Environmental Quality Act, but he said he wasn't aware of what Brown planned to propose.

"We'll listen to anything that the administration has to say about it," Steinberg said, "but it hasn't really come up directly."